Molecular analysis of HLA-DQ A alleles in coeliac disease lack of a unique disease-associated sequence.

Susceptibility to coeliac disease is strongly associated with some HLA class II antigens, encoded by the HLA-D region. Since the HLA-DQ locus seems to be primarily involved, we have analysed by polymerase chain reaction amplification and allele-specific oligonucleotide hybridization the most polymorphic region of the HLA-DQ A1 gene. No difference was observed between the 20 coeliac patients and 20 HLA-D-matched healthy controls who took part in the study. Furthermore, in patients and controls, the restriction fragment length polymorphism analysis of the HLA-DQ A gene using the restriction enzyme BglII did not disclose any specific disease-associated fragment. Our results are not consistent with a unique DQ A coeliac disease-associated sequence, but rather with the hypothesis that some polymorphic residues or allelic hypervariable regions, although found also in the normal population, can predispose to coeliac disease due to their higher frequency in this condition.